From: Sabrina Dubroca sd@queasysnail.net
[ Upstream commit feadc4b6cf42a53a8a93c918a569a0b7e62bd350 ]
Currently, nla_put_iflink() doesn't put the IFLA_LINK attribute when iflink == ifindex.
In some cases, a device can be created in a different netns with the same ifindex as its parent. That device will not dump its IFLA_LINK attribute, which can confuse some userspace software that expects it. For example, if the last ifindex created in init_net and foo are both 8, these commands will trigger the issue:
ip link add parent type dummy # ifindex 9 ip link add link parent netns foo type macvlan # ifindex 9 in ns foo
So, in case a device puts the IFLA_LINK_NETNSID attribute in a dump, always put the IFLA_LINK attribute as well.
Thanks to Dan Winship for analyzing the original OpenShift bug down to the missing netlink attribute.
v2: change Fixes tag, it's been here forever, as Nicolas Dichtel said add Nicolas' ack v3: change Fixes tag fix subject typo, spotted by Edward Cree
Analyzed-by: Dan Winship danw@redhat.com Fixes: d8a5ec672768 ("[NET]: netlink support for moving devices between network namespaces.") Signed-off-by: Sabrina Dubroca sd@queasysnail.net Acked-by: Nicolas Dichtel nicolas.dichtel@6wind.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/rtnetlink.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)
--- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1496,14 +1496,15 @@ static int put_master_ifindex(struct sk_ return ret; }
-static int nla_put_iflink(struct sk_buff *skb, const struct net_device *dev) +static int nla_put_iflink(struct sk_buff *skb, const struct net_device *dev, + bool force) { int ifindex = dev_get_iflink(dev);
- if (dev->ifindex == ifindex) - return 0; + if (force || dev->ifindex != ifindex) + return nla_put_u32(skb, IFLA_LINK, ifindex);
- return nla_put_u32(skb, IFLA_LINK, ifindex); + return 0; }
static noinline_for_stack int nla_put_ifalias(struct sk_buff *skb, @@ -1520,6 +1521,8 @@ static int rtnl_fill_link_netnsid(struct const struct net_device *dev, struct net *src_net) { + bool put_iflink = false; + if (dev->rtnl_link_ops && dev->rtnl_link_ops->get_link_net) { struct net *link_net = dev->rtnl_link_ops->get_link_net(dev);
@@ -1528,10 +1531,12 @@ static int rtnl_fill_link_netnsid(struct
if (nla_put_s32(skb, IFLA_LINK_NETNSID, id)) return -EMSGSIZE; + + put_iflink = true; } }
- return 0; + return nla_put_iflink(skb, dev, put_iflink); }
static int rtnl_fill_link_af(struct sk_buff *skb, @@ -1617,7 +1622,6 @@ static int rtnl_fill_ifinfo(struct sk_bu #ifdef CONFIG_RPS nla_put_u32(skb, IFLA_NUM_RX_QUEUES, dev->num_rx_queues) || #endif - nla_put_iflink(skb, dev) || put_master_ifindex(skb, dev) || nla_put_u8(skb, IFLA_CARRIER, netif_carrier_ok(dev)) || (dev->qdisc &&